Delta CG determination
08-20-2002, 11:18 AM
#1
Senior Member
Thread Starter
Delta CG determination
Get these dimensions:
Root chord (including the elevons)
Tip chord "
span
sweep
Most deltas will fly with the c.g. no further back than 25% MAC..
then go to:
http://www.palosrc.com/instructors/cg.htm
Root chord (including the elevons)
Tip chord "
span
sweep
Most deltas will fly with the c.g. no further back than 25% MAC..
then go to:
http://www.palosrc.com/instructors/cg.htm
08-20-2002, 07:21 PM
#2
Senior Member
Thread Starter
Delta CG determination
This is one of those areas where you have to know part of the answer to get the whole answer.
Plank-reflexed airfoiled wings for instance generally fly well with c.g.s in the 12-15% range, while a delta can go back to 25%.. if you want a responsive plane.
Don't go aft of 25% if the plane is tailless though. It won't fly long!
Plank-reflexed airfoiled wings for instance generally fly well with c.g.s in the 12-15% range, while a delta can go back to 25%.. if you want a responsive plane.
Don't go aft of 25% if the plane is tailless though. It won't fly long!
08-21-2002, 09:45 AM
#3
Senior Member
Join Date: Aug 2002
Location: Georgetown,
TX
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
Another Delta CG method
I am not an expert but I was told one of the best ways to locate the CG was to use the rear landing gear if it has it, the CG should be slightly forward of the gear, say 15 degrees from the rear axle.
09-13-2002, 07:44 PM
#4
Senior Member
Thread Starter
Delta CG determination
Originally posted by Arthur Dodd
Ollie,
Not pulling your leg! That's a lot of sq in area to expect it to remain stiff and also not warp. 1/4" balsa ply really seems to be a good choice since it is only a little heavier than sheet stock and a lot stronger.
.
A Warren Girder construction of 1/4" sq. balsa and 1/4"x1/2" balsa is adequate, and stiff enough when covered with Monokote.
And a 4" root chord will be OK.
.
There will be a dedicated servo for each aileron, a standard type servo. i.e., cheap Tower item, acting on the aileron 1/3 of it's length from the fuse.
.
You get what you pay for. Cheap will strip in flight.
,
1) Should I add to the ailerons? I was thinking of attaching 1/8" balsa ply to the ailerons so that they would extend behind the ailerons 3" and be 6" long. Like flaps that are locked to the ailerons.
.
???
Without knowing what the flight characteristics are or might be, why add anything?
.
2) If this is done, where should the flaps be located; near the fuse or near the wing tips?
.
fly it first, then decide..
.
Arthur
Ollie,
Not pulling your leg! That's a lot of sq in area to expect it to remain stiff and also not warp. 1/4" balsa ply really seems to be a good choice since it is only a little heavier than sheet stock and a lot stronger.
.
A Warren Girder construction of 1/4" sq. balsa and 1/4"x1/2" balsa is adequate, and stiff enough when covered with Monokote.
And a 4" root chord will be OK.
.
There will be a dedicated servo for each aileron, a standard type servo. i.e., cheap Tower item, acting on the aileron 1/3 of it's length from the fuse.
.
You get what you pay for. Cheap will strip in flight.
,
1) Should I add to the ailerons? I was thinking of attaching 1/8" balsa ply to the ailerons so that they would extend behind the ailerons 3" and be 6" long. Like flaps that are locked to the ailerons.
.
???
Without knowing what the flight characteristics are or might be, why add anything?
.
2) If this is done, where should the flaps be located; near the fuse or near the wing tips?
.
fly it first, then decide..
.
Arthur
09-13-2002, 09:08 PM
#5
Banned
Join Date: Jan 2003
Location: gone,
Posts: 4,923
Likes: 0
Received 0 Likes
on
0 Posts
Delta CG determination
without knowing the expected max airspeed of the model, its impossible to say what servo would be adequate for the aileron loads.
The Tower TS-53 is a relabeled Futaba S-3003, and I'm assuming thats what you mean by a cheap Tower servo. In dual servo for ailerons setups, these are adequate for almost any common .40 size aircraft, but can be stripped out by aileron flutter fairly easilly in a plane such as a 4*60 set up for max speed using a strong .61 2-stroke. (and that's not a fast plane...)
If your wing will be flying under 50 mph all the time and the linkages are slop free and the hinge line has minimal gap... you shouldn't have problems. If you plan to go faster, get better servos. I'm betting you need an upgrade.... Fast with big control surfaces and a "standard" servo... asking for trouble.
Simply getting the EMS ball bearing kit for the S-3003/TS-53 might help considerably....appx $15 to convert 4 servos and has flex-free glass filled nylon case tops and servo output arms virtually eliminating 3 control slop sources. Might consider 4-40 size pushrods too.... less rod flex. Heavy duty bolt-on ball link one end and soldered clevice the other. (virtually no play in linkage at that point. a big help in flutter perevention.)
Prevent the flutter before you fly... its awful hard to cure after you take off.
The Tower TS-53 is a relabeled Futaba S-3003, and I'm assuming thats what you mean by a cheap Tower servo. In dual servo for ailerons setups, these are adequate for almost any common .40 size aircraft, but can be stripped out by aileron flutter fairly easilly in a plane such as a 4*60 set up for max speed using a strong .61 2-stroke. (and that's not a fast plane...)
If your wing will be flying under 50 mph all the time and the linkages are slop free and the hinge line has minimal gap... you shouldn't have problems. If you plan to go faster, get better servos. I'm betting you need an upgrade.... Fast with big control surfaces and a "standard" servo... asking for trouble.
Simply getting the EMS ball bearing kit for the S-3003/TS-53 might help considerably....appx $15 to convert 4 servos and has flex-free glass filled nylon case tops and servo output arms virtually eliminating 3 control slop sources. Might consider 4-40 size pushrods too.... less rod flex. Heavy duty bolt-on ball link one end and soldered clevice the other. (virtually no play in linkage at that point. a big help in flutter perevention.)
Prevent the flutter before you fly... its awful hard to cure after you take off.
